CN109963526B - Stent and stent implantation method - Google Patents

Abstract

A stent for deployment in the eustachian tube and other body passages is disclosed which supports the walls and assists in the natural opening of the passage without interfering with the natural closing operation.

Description

Stent and stent implantation method

Technical Field

The present disclosure relates to a stent, in particular for placement within the eustachian tube, and a method of implanting a stent for such placement.

Background

References considered to be relevant as background to the subject matter of the present disclosure are listed below:

bluestone, cd.european Tube Structure, Function, Role in otis Media (eustachian Tube Structure, Function, Role in Otitis Media) BC Decker Inc; hamilton, Anda 2005

Bluestone, CD.; klein JO.Otitis Media in Infants and Children (otitis Media in Infants and Children). BC Decker; 2007 to Hamilton, Anda

Stephen Chad Kanick and William J. Doyle, Barotrauma during air travel: predictions of the baromatic model J Appl Physiol 98: 1592-. First published in 2004 at 12 months and 17 days

F.J.Sheer, J.D.Swarts and S.N.ghadiali, Three-dimensional cosmetic Element Analysis of Eustatic Tube Function under Normal and Pathological Conditions, Med Eng.Phys.2012,34(5):605-

Poe DS et al, Analysis of Eustachian tube function by video endoscope, Am J Otol.2000; 21:602-607

6. International published patent application WO 2009/001358

7. U.S. Pat. No. 9,510,976

8. U.S. Pat. No. 6,589,286

The identification of the above references herein should not be inferred to mean that these are linked in any way to the patentability of the presently disclosed subject matter.

Background

Adequate ventilation and drainage are critical to normal middle ear function, and it is the Eustachian Tube (ET) that normally provides this function. Chronic eustachian tube dysfunction is closely associated with the pathogenesis of many otological diseases and is considered to be a major cause of failure of various otological procedures. Chronic middle ear disease patients often show a mechanical narrowing with an ET, usually at the isthmus (the junction of the bone and cartilage portions). ET dysfunction is also associated with functional disorders of the cartilage portion.

The eustachian tube is normally closed in a resting position and is normally expanded to an open position under swallowing, yawning and other voluntary or involuntary efforts. The opening of the tube typically lasts less than half a second. The closing of the eustachian tube is maintained by valvular function of the opposing mucosal surfaces, submucosal tissue, fat, muscle and cartilage. This native valve (natural valve) is about 5mm in length and is located within the cartilaginous portion of the ET, which is located about 10mm from the tubular distal end of the posterior pad of the nasopharyngeal orifice or the eustachian tube pillow.

A common problem caused by eustachian tube dysfunction is otitis media with effusion (OME), or the presence of fluid in the middle ear without signs or symptoms of acute ear infection. The persistent middle ear fluid of OME causes reduced mobility of the tympanic membrane and is an obstacle to sound conduction. OME may occur spontaneously due to eustachian tube dysfunction or a response following acute otitis media. This may occur in infants and children 1-6 years old due to anatomical differences and physiological changes in the eustachian tube. At birth, the tube is horizontal and approximately 17-18mm long. During adulthood, it grows with a slope of about 45 degrees and reaches a length of about 35 mm. These subjects are more likely to suffer from eustachian tube dysfunction due to their relatively horizontal position and relatively short length in infants and young children.

Most surgical procedures performed to treat these body conditions involve bypassing the occluded ET by implanting a surgical prosthesis (usually in the tympanic membrane (eardrum)) in order to ventilate the middle ear cavity via the external auditory canal. Tympanostomy tubes are recommended for initial surgery. However, such tubes often suffer from complications. Early complications include: sustained ear leakage 10% -26%, tube blockage 0-9%, early extrusion (early extrusion), and hearing loss. Late complications include: 3% of persistent perforation after tube extrusion, 21% -28% of tympanic membrane scarring, atrophic membrane, 5% -40% of granuloma, 40% -65% of tympanostomy, and 1% of cholesteatoma.

US 6,589,286 and WO 2009/001358 disclose scaffolds for deployment in an ET ("ET scaffold"). While the former generally discloses such stents, the stents specifically disclosed and shown in the drawings of WO 2009/001358 have lobes that enhance ventilation and drainage of the middle ear and a method of stent implantation for insertion of the stent into the ET.

US 9,510,976 discloses an ET holder having a length-dependent radial strength to allow it to stay within the ET and allow normal closing and opening of the ET.

SUMMARY

The present disclosure provides stents, stent deployment assemblies (including stents, stent delivery systems, and optional stent removal devices), and methods of stent implantation. The stent of the present disclosure has a unique design that makes it suitable, but not exclusive, for deployment in the Eustachian Tube (ET) and assists in the natural opening of the ET without interfering with the natural closing operation. Reference to ET scaffolds in the following of the present disclosure denotes ET scaffolds that embody the characteristics of the scaffolds provided by the present disclosure.

In addition to serving as ET stents, stents embodying features of the present disclosure may be adapted to complement and assist in the natural opening operation of other variable body passages without interfering with the natural closing operation. The stents of the present disclosure may also be configured, for example, for deployment in the biliary tract for the treatment of Oddi sphincter dysfunction (SOD), in which the sphincter may be dysfunctional, not letting through digestive fluids that it should otherwise let through; or configured for deployment in the esophagus for treating lower esophageal sphincter or upper esophageal sphincter dysfunction; or configured for deployment in the urethra for treating urethral sphincter dysfunction.

The stent of the present disclosure is a collapsible stent whose function is to open a blocked or obstructed lumen (lumen) while being adapted to allow natural closing and opening of the lumen. For example, the ET holder is configured to support the walls of the ET, thereby facilitating pressure equalization of fluid drainage from the middle ear to the nasopharyngeal cavity and into the middle ear, while allowing closure of the ET's native valve.

According to one embodiment, the stent has a support frame (scaffold) formed by struts shaped to form cells (cells) within the support frame, which cells may be open cells or closed cells or a combination of both. The properties of the struts (e.g., width, thickness, etc.) and the properties of the cells (e.g., size, whether the cells are open cells or closed cells, or the relative proportions of open cells and closed cells) are parameters that affect the flexibility and rigidity of the support frame. Stents are typically designed to be oversized (i.e., the stent expands without obstruction to a cross-sectional dimension that is larger than the cross-sectional dimension of the lumen in which the stent is deployed), and the degree of oversizing may also be important to controlling the flexibility or stiffness of the stent. These features are typically achieved without any structural discontinuities in the struts.

It has also been realized according to some embodiments of the present disclosure that the function of opening a variable channel (e.g., ET) on the one hand and allowing natural closing on the other hand can be best achieved by a stent that is not axially symmetric, but has a longitudinal plane of symmetry, wherein the two sides of the stent are mirror images of each other. For example, the portion of the ET proximal to the nasopharyngeal cavity acts as a natural valve because its walls can collapse, closing the channel; and open by moving away from each other via contraction of the surrounding smooth muscle. For example, opening occurs in response to a swallow or yawning action. However, the constriction of many sphincters in a tubular passage is not performed in an axially symmetric manner, but is achieved by a cooperative displacement of two opposing wall portions towards each other. The stents of the present disclosure are particularly useful for deployment in tubular passageways in the body having sphincters for closing and opening the passageways in a non-axially symmetric manner.

Thus, a particular embodiment of the stent of the present disclosure is a stent that embodies the features described above and has a longitudinal plane of symmetry (a plane defined and extending along the axis of the stent) rather than an axial plane of symmetry. According to this embodiment, the stent has a peripheral support shelf that is inherently biased to an expanded state, which is a state in which the support shelf is extended to its fullest extent. In this expanded state, the stent has a length defined between the proximal and distal ends of the stent scaffold. As mentioned above, the support shelf of the rack has a longitudinal plane of symmetry extending lengthwise along the rack between the ends. In other words, the supporting brackets of the stand, although not axially symmetrical, have two sides which are mirror images of one another.

The holder of this embodiment is characterized in that an inwardly directed force on the mirror side in a direction perpendicular to the plane of symmetry results in an inwardly directed displacement, which is however larger than the displacement resulting from the same inwardly directed force exerted in a direction parallel to said plane of symmetry. In other words, the stent reacts differently to radial forces in different directions, so that a force applied in a direction perpendicular to the longitudinal symmetry plane exerts a weaker displacement resistance than a force applied in a direction perpendicular to the longitudinal symmetry plane.

In the following description, the term "axial" is used to refer to the general orientation defined by the axis of the stent (extending between the ends of the stent), but it will be understood that once deployed, the stent may not be perfectly straight, and thus the axis may be curved; the term "vertical" is used to denote a direction perpendicular to the axis and to the plane of symmetry. Furthermore, the terms "proximal" and "distal" are used with respect to the direction of insertion and deployment thereof; for example, in the case of ET stents, the proximal end or proximal segment is closest to the nasopharyngeal cavity. The term "lumen" or "channel" is used to refer to such structures within the body.

The stent of the present disclosure will be described hereinafter occasionally with reference to ET stents, which description is intended to illustrate the teachings of the present disclosure and is not intended to be limiting in any way.

In use, the ET mount is deployed such that its transverse support frame portions bear on the transverse wall portions of the ET. Thus, when the ET transverse walls, and in particular the proximal transverse walls, constitute the native valve, these transverse walls support and act on the weaker parts of the support frame walls. The transverse portions of the support shelf are configured to be resilient such that they expand with the transverse walls during expansion and opening of the walls, and also provide relatively little resistance that does not impede collapse of the walls to seal the channel. In other words, while the ET stent adds support to the opening, it does not serve to cause the channel to remain constantly open and thus contributes to the natural valve function.

As noted, the stents of the present disclosure are generally non-axially symmetric. Furthermore, the entire cross-section of the stent, mainly in the proximal section, is non-circular and may be, for example, oval or elliptical.

The ET stent may be configured to deploy only in a proximal portion of the ET; or the ET stent may be configured to deploy only in the cartilaginous portion of the ET, and may be disposed along the cartilaginous portion or only a portion thereof; or the ET stent may be configured to be positioned along or avoiding the native valve; or the ET stent may be configured to expand to fill a greater portion of the length of the ET.

According to some embodiments of the present disclosure, the stent may have a relatively uniform cross-sectional shape and size along its axis, in other embodiments the stent may have a different cross-section to fit different portions of the channel; for example, in the case of an ET stent, the proximal cross-section of the stent may be larger than the distal cross-section.

The size (length and diameter) of body organs and passages within the body (e.g. ET) vary with age, and therefore stents in this respect can be designed with different sizes depending on their target population: for example, small racks for infants, toddlers, or young children and larger racks for older children or adults.

According to one embodiment, the ET mount has a carrier frame comprising an array of cells. The cells may be closed cells, open cells, or a combination of both. The structural characteristics of the unit affect the flexibility and displacement resistance properties of the support frame. These structural features include, for example, the relative proportions of open and closed cells, the overall size and configuration of the cells, and the physical properties of the struts. For example, the relative proportions of open cells and closed cells may be different in different portions of the support frame, thereby imparting different physical properties (including flexibility and displacement resistance) to different portions of the support frame. This can also be achieved by having different sized units in different sections (a larger unit generally results in a carrier with greater flexibility and lower resistance to displacement than a section with a smaller unit). Larger cells or a high proportion of open cells may typically be located at the lateral portions of the support shelf.

According to one embodiment, the supporting frame of the stent is formed by substantially zigzag-shaped, Z-shaped or sinusoidal struts extending between two opposite ends of the supporting frame. The struts form oppositely directed apices. Two consecutive vertices having the same orientation are separated from each other by a vertex distance (referred to herein as vertex distance); and two consecutive opposing vertices are separated from each other by lateral distances defined between tangents to the vertices, which will be referred to herein as amplitude lengths (amplitude lengths).

In some embodiments, the opposing apices of adjacent struts are circumferentially (circularly preferentially) connected to form a closed cell, or some may not be connected to form an open cell. The different flexibility and resistance to displacement of the different parts of the stent may be achieved by variation in the nature and configuration of the struts, which may be one or more of: (i) a change in vertex distance; (ii) a change in amplitude length; and (iii) a change in struts in at least one portion of the scaffold as compared to at least one other portion.

According to one embodiment of the disclosure, the support has a support frame which is composed of two mirror-symmetrical parts which are connected to one another only at the ends of the support. This bracket will be referred to as "mirror symmetric bracket" hereinafter. Although according to some embodiments the two parts of the mirror-symmetrical holder may be hinged to each other at both ends thereof, the two parts are typically integrally formed. The mirror-symmetrical stent is also inherently biased to an expanded state having the noted longitudinal plane of symmetry extending between the ends of the stent. Unlike conventional brackets which have a plurality of transverse connections between different parts or portions of the support frame, the two mirror image portions of the support frame of a mirror image bracket are typically connected to each other only at their ends. This inherently configures the stent to have such physical properties that an inwardly directed lateral force (i.e. a force perpendicular to a longitudinal plane of symmetry extending axially between the two portions) results in an inwardly directed displacement; while a vertical force applied parallel to the plane causes no or little displacement. Furthermore, such lateral displacement occurs without any deformation in the other portions of the stent (which may occur upon inward displacement of the lateral portions in the case where the stent constitutes a continuous circumferential structure).

The support shelf of a mirror-symmetrical rack typically has an overall non-circular cross-section, with two opposing mirror-image portions typically defining opposing generally vertical and sometimes outwardly curved planes.

The mirror-symmetrical bracket may include two or more struts extending between the ends, the two or more struts being integrally joined with mirror-image struts in opposite portions of the support shelf. The struts may be interconnected by transverse elements, such as transverse rods that span the width between the struts.

According to some embodiments, the struts may also have an overall configuration similar to the struts described above having a generally sinusoidal, zig-zag or Z-shaped configuration, thereby forming an open cell or a closed cell.

Stents are generally configured such that, when the stent is in its expanded state, at least a portion of the stent has a size greater than the corresponding portion of the lumen in which the stent is to be deployed. This large size means that the stent will naturally expand to a slightly larger size than the corresponding portion of the lumen. This oversize results in the stent exerting a constant force on the walls of the channel, and this fact, and the oversize variations between different axial positions, can assist in holding the stent in place and avoiding migration.

According to some embodiments, the ET mount may include elements intended to aid in mount removal. These elements may be, for example, integrally formed with the carrier, or may be non-integral elements that are joined or tied to the carrier in some manner. An example of such an element is a trailing arm (trailing arm) formed at the proximal end by the braided connecting ends of the struts of the stent, which may be a wire (thread), cable (cable), wire (wire), suture (stitch) or tab (tab).

According to one embodiment, an arm, cable or tab attached to the proximal end of the ET stent may extend from the aperture of the ET and protrude into the nasopharyngeal space. The arm, cable, or tab may pass through the native valve at the aperture of the ET and may engage an anatomical feature (e.g., muscle) that moves when swallowed. Upon such engagement, the arm, cable or tab may be pushed and exert pressure on the native valve. The native valve will be forced open and the ET allowed to ventilate.

According to some embodiments of the present disclosure, the stent includes anchoring elements integrally formed with the stent, the purpose of which is to hold the stent in place to avoid migration thereof.

The stents of the present disclosure may be made from a variety of materials, such as nitinol, stainless steel, cobalt chromium, various other metals, silicone rubber, various polymeric materials, particularly biodegradable materials or bioabsorbable materials (e.g., polylactide-based materials).

In other embodiments, the stent may be made of one material and coated with another material, such as, for example, nitinol struts coated with a polymeric material.

According to some embodiments, the stent of the present disclosure may also be configured to elute a drug (elute) to its surrounding tissue. Drugs that may be included in such drug eluting stents include, for example, steroids, anti-inflammatory drugs, antibiotics, and the like. Techniques for incorporating drugs into drugs are well known.

Stents may be made by various manufacturing techniques, such as laser cutting, braiding, 3D printing, injection molding, compression molding, and the like. According to some embodiments, the stent may be configured.

As also noted above, the present disclosure provides a delivery system for deploying a stent, which may include a delivery catheter that is inserted through a nostril, preferably using a scope guide in the case of an ET stent. The delivery system may be based on this approach commonly used to deliver self-expanding stents and may include an outer sheath for compressing the stent to a small diameter and an inner sheath over which the stent is compressed. The delivery system may further include a guide wire (guide wire) for guiding the advancement of the inner sheath. Once in place, the outer sheath may be pulled back to expose the stent and allow it to expand; and after deployment, the inner sheath may also be retrieved. The steering end of the catheter may be provided with markings to assist in the safe deployment of the stent.

Prior to the stent implantation procedure of the present disclosure, a channel balloon expansion (similar to the balloon expansion performed in angioplasty) may be performed that is intended to apply radial compression to the wall, expand the opening, and express fluid and mucus. Such site preparation may facilitate the stent implantation process and allow the stent to fully expand within the passage to achieve full engagement with the surrounding tissue.

Brief Description of Drawings

In order to better understand the subject matter disclosed herein and to exemplify how it may be implemented in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

fig. 1 is a schematic illustration of a stent deployed in an ET according to one embodiment of the present disclosure.

Fig. 2A and 2B are views in ET open and closed states, respectively, as viewed from the direction of arrow II in fig. 1.

Fig. 3 shows a stent of one embodiment of the present disclosure having different dimensions in different portions along its length to fit the corresponding portion of the ET, and configured such that its proximal end will protrude out of the ET to allow removal of the stent.

Fig. 4 shows a stent configured for deployment in a specific portion of the ET, typically within the cartilaginous portion distal to the native valve.

Fig. 5 shows a stent of the present disclosure provided with a braided tail.

Fig. 6 is a schematic view of a stent having depending legs extending into the nasopharyngeal cavity.

FIG. 7 is a schematic view of one embodiment of a mirror-symmetric stent.

Detailed Description

The invention will now be further described with reference to some specific embodiments which are schematically depicted in the drawings. These examples relate to ET mounts, but it should be understood that these examples are intended to illustrate and exemplify the teachings of the present disclosure, and are in no way intended to be limiting; rather, they are examples of the broader teachings of the present disclosure.

Referring first to fig. 1, astent 100 according to one embodiment of the present disclosure is shown, thestent 100 deployed within an ET. Thestent 100 has aperipheral support shelf 102 formed by a plurality ofstruts 104, thestruts 104 following a generally sinusoidal path extending between aproximal end 106 and adistal end 108 of the stent. In adjacent struts of such a sinusoidal configuration, opposing vertices are connected to one another at connection points 110, thereby defining a plurality ofclosed cells 112.

As can be seen in fig. 2A, the stent has an overall elliptical or oval cross-section defining a longitudinal plane of symmetry indicated by the dashedline 120, divided between two sides that are mirror images of each other. Thus, the bracket is configured such that an inwardly directed force in a direction perpendicular to plane 120 (as indicated by arrow 122) results in a greater displacement than a similar force applied in a vertically inward direction (as indicated by arrow 124). Thus, when the wall proximal to the ET is closed when the surrounding smooth muscle relaxes from the open state shown in fig. 2A to the closed state shown in fig. 2B, the two transverse walls displace inwardly, allowing the valve to close.

Figures 3-5 illustrate different stent configurations.

In fig. 3,stent 130 has segments of different cross-sectional dimensions including adistal segment 132 having a narrow dimension; and aproximal section 134 having a wider dimension. The cells insegment 134 are larger and therefore have a greater apex distance and/or amplitude length, and accordingly the stiffness and displacement resistance is generally lower than indistal segment 132. The cell size, apex distance and amplitude length may also vary in the upper and lower portions as compared to the transverse portion of the stent.

Fig. 4 shows astent 138, thestent 138 configured to be deployed in only a portion of the ET, and fig. 5 shows astent 140, thestent 140 having a trailingend 142 made up of the braided end of the strut.

Fig. 6 shows abracket 146 havingarms 148, thearms 148 being attached to aproximal end 150 of a support frame. The stent is deployed in the ET cartilage portion distal to the native valve at the proximal end of the ET, and thus thearms 148 engage anatomical features (such as muscles) that move when swallowed through the native valve. In this engagement, thearms 148 are pushed and exert pressure on the native valve. The native valve will be forced open and allow ET ventilation.

Fig. 7 shows a mirror-symmetric stent 160, thestent 160 comprising two mirror-symmetric portions 162A and 162B extending longitudinally between proximal and distal ends and includingrespective strut connectors 164A, 165A and 164B, 165B, each strut connector being integral with its mirror-image strut atintegration points 170 and 172. The strut connectors are interconnected by a pair oftransverse rods 166A, 167A and 166B, 167B. Each of theportions 162A and 162B forms a generally vertical, slightly outwardly curved plane. This configuration provides flexibility of the support shelf in the lateral direction only near theintegrated terminations 170 and 172 and allows very little, if any, inwardly directed vertical displacement.

It will be appreciated that the above-described brackets are deployed such that the vertical portions of the brackets are juxtaposed with the lateral portions of the channel and thus allow some lateral inward displacement of the walls.

The stent of the present disclosure may be anchored by forces generated by changes in radial force, changes in cross-section, and/or changes in its eccentricity along its longitudinal axis.

The stent of the present disclosure may also include means to hold the stent in place and avoid migration. Such means may include a rod or other protrusion that protrudes from the cylindrical housing of the bracket and anchors the bracket in place. Where the stent is made by laser cutting, such rods or other protrusions may be formed at multiple locations along the length of the stent. Alternatively, the serrations of the laser cut stent may be configured to protrude from the cylindrical profile of the stent ("ichthy") and help to resist migration.

Claims (17)

1. A stent having a peripheral scaffold, the scaffold being inherently biased into an expanded state, the stent having a length defined between a proximal end and a distal end of the scaffold; wherein

The support shelf has a longitudinal plane of symmetry extending along the support shelf between the ends; wherein

An inwardly directed force in a direction perpendicular to the plane of symmetry results in an inwardly directed displacement that is greater than a displacement resulting from the same inwardly directed force applied in a direction parallel to the plane of symmetry; wherein

The inwardly directed force causes no or little displacement in a direction parallel to the plane of symmetry; and wherein

The support shelf includes an array of cells, wherein cells in at least one portion of the support shelf have a different size than cells in at least one other portion.

2. The stent of claim 1 wherein the support stent is non-axially symmetric.

3. The stent of claim 2 wherein the support stent has a non-circular cross-section.

4. A rack as claimed in claim 2 wherein the support shelf is formed from two mirror image sections joined to each other at both ends.

5. The stent of claim 1, wherein the cells are one or a combination of closed cells and open cells.

6. A stent as claimed in claim 1 comprising open cells and closed cells and wherein the relative proportions of closed cells and open cells are different in different parts of the stent frame.

7. The stent of claim 1 wherein the stent is formed from generally serrated struts extending between two opposing ends, the struts having oppositely oriented apices, two successive apices of the same orientation being separated from each other by an apex distance, and two successive apices that are opposite being separated by an amplitude length.

8. The stent of claim 7, wherein the struts define a substantially sinusoidal or Z-shaped curve.

9. The stent of claim 7, wherein opposing apices of adjacent struts are circumferentially connected to define a radial ring.

10. The stent of claim 7, wherein one or more of (i) the apex distance, (ii) the amplitude length, and (iii) the width of the strut in at least one portion of the support shelf is different than in at least one other portion.

11. The stent of claim 10, wherein the scaffold is configured such that a confining force applied at the proximal end results in a greater displacement than a confining force applied at the distal end.

12. The stent of claim 1, wherein the stent has a larger dimension in at least a portion of the stent than a corresponding portion of the lumen in which the stent is to be deployed when the stent is in its expanded state.

13. The stent of claim 1, comprising a trailing arm at the proximal end to aid in stent removal.

14. The stent of claim 1, comprising a wire, cable, wire, or tab at the proximal end to aid in stent removal, the wire comprising a suture.

15. A bracket as claimed in claim 1 which includes an anchoring element integral with the support shelf.

16. A stent according to claim 1 for deployment in a eustachian tube.

17. A stent deployment assembly comprising the stent of claim 1 and a stent delivery system.

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